The Jazz Guitar Chord Dictionary
Reply to Thread Bookmark Thread
Page 2 of 2 FirstFirst 12
Posts 26 to 35 of 35
  1. #26

    User Info Menu

    Special thanks to Dan Shinn and company of Lays Guitar in Akron Ohio for re installing the back binding and touching up the lacquer.
    Attached Images Attached Images Unfortunate top brace fitting in new Gibson ES-275-img_0801-jpg Unfortunate top brace fitting in new Gibson ES-275-img_0802-jpg 

  2.  

    The Jazz Guitar Chord Dictionary
     
  3. #27

    User Info Menu

    Quote Originally Posted by Ol' Fret
    Yes, a tall and thin parabolic tonebar profile would be ideal!
    Ok, let's not be more papal than the pope, time is money! Something like approximate parabolic profiles can be prefabricated and would be desirable in any serial production.

    Attachment 64101
    If the only purpose of the brace is to provide maximum supporting stiffness with minimum weight, removing material from the outer edge by tapering produces exactly the opposite effect. The ideal brace would surely have an 'I' cross section like a girder.
    In fact, if you consider a kerfed brace, having many quite wide kerfs and being glued in place with care so that it looks like a spaced series of small blocks joined at the top by a solid strip that would be loaded in compression, would you not have an ideal low mass stiffener?

    Arthur

  4. #28

    User Info Menu

    This is actually a brace design that has been experimented with in the violin world. You fit a bass bar that has interrupted sections or "cut outs". It hasn't really caught on for some reason, but it is commonly used to allow you to fit crack repair cleats under the bass bar when the crack runs right along the bar.
    Attached Images Attached Images Unfortunate top brace fitting in new Gibson ES-275-bar-jpg 

  5. #29

    User Info Menu

    That really is shamefully sloppy; how can Gibson fall so low and not die of shame? That's only the 2nd example I've seen so far - the other was a new SG with the finish peeling off the headstock and outright broken off the neck, as if someone had quickly frozen and thawed it, then dipped the headstock in nailpolish remover - but in both cases it's grotesque "don't care, will sell" rather than a little negligence. Very disappointing.

    p.s. I like your double bass site

  6. #30

    User Info Menu

    << If the only purpose of the brace is to provide maximum supporting stiffness with minimum weight, removing material from the outer edge by tapering produces exactly the opposite effect. <<


    Providing stiffness is the main function of tone bars. Tapering the ends of the bars towards the plate - where the string load is insignificant - is essential from the engineering point of view in order to get a maximum smooth transition without abrupt weak spots or places of mechanical (and vibrational) discontinuity. Ideally, the bars would taper out flat to the plate surface.

    The making of fine acoustic archtop guitars is all 1. about mechanical stiffness, and 2. smooth propagation of waves. This is the same as are tap tuning methods used by some luthiers. Stiffness translates into tap tone, and vice versa. Some feel it, some others hear it, again some others use both approaches, the majority uses empirical standards (that can vary a lot depending on the wood, the construction, the intended sound ideal, the continent, the actual musical fads, etc.). And the industry workers have to follow fixed values. Period.

    It would probably make not much difference if you'd use elaborated shaped tonebars or simple rectangular braces in a guitar construction like the ES-275, so Ockham's Razor would be appropriate.

    Also, there's a reason why archtop luthiers don't elongate the tone bars by glueing them into the blocks or the lining (which should provide even more stiffness): the body construction has to be as stiff as possible, at the same time allowing the plates to resonate freely and undisturbed. That's why most acoustic archtops feature the arched construction, bracing only where it is necessary, and two lateral f-holes.

    Girder in architecture or technical construction, etc., follow the same physical principals as our archtop guitar's bracing, but buildings or airplanes are built to prevent and avoid vibrations and resonances. The construction of a new main spar for an aerobatic plane is demanding. Two goals are the same as with our tonebars: to provide maximal stiffness at lowest weight. But, again, (uncontrolled) vibrations and resonances are the enemy of strictly static constructions. Airplane constructions with simple rectangular dimensioned and crafted wooden spars were not longer used after the 1930s. Watching the tone bars of many a new archtop guitar reminds us that we're still living in the archtop guitar Stone Age. As an excuse we have to consider that after the 1950s the further development of the acoustic archtop guitar halted, except visual embellishments.

    The theory of bracing was developed in the 19th century. It is called 'parallel axis theorem' or 'Huygens-Steiner theorem' - and no, this is not useless knowledge, but the daily bread of many engineers worldwide, except most luthiers.
    If luthiers would understand or follow Steiner, they'd immediately dump down any thoughts about 'kerfed' tone bars. Or about routing (integrate) bars out of the soundboard wood. Such constructions follow solely cost-cutting or marketing standards, result in overbuilding (or failure) and worse stiffness-weight relations.
    Newer developments, like the use of composites, etc., would make sense. However, luthiers are woodworkers, sticking to wood as their main material. Ok, wood is sustainable and ecofriendly. So, please, for acoustic archtop guitars, give the wood the best possible shape!






  7. #31

    User Info Menu

    This approach works quite well:
    Attached Images Attached Images Unfortunate top brace fitting in new Gibson ES-275-hof-new-president-bracing-jpg 

  8. #32

    User Info Menu

    Funny, I now own 3 hollowbodies without bracing. Two of those have the typical Asian low budget construction of a sound post under the bridge instead of tone bars to prevent the top from sinking (the third - as you all might know by now - is my ES-125 that came to me with the tonebars missing so the sound post was a necessity). I find that this way of constructing hollowbodies yields nearly identical sound results as the construction with tone bars.... (These guitars all have laminated tops, so I don’t know if the same goes for solid or even carved tops - but I don’t think so). In my Japanese ES-175 copy I experimented with glueing in tone bars (between neck and bridge, since longer tonebars wouldn’t fit thru the pickup cavities). Big no-no! The tone became very brittle and treble-ish.... removed them and the nice woody thunk this guitar had was back (I had a suspicion so thankfully I used water solvable wood glue). So apparently restricting top movement too much and making it too stiff emphasises the trebles and results in a very thin tone.

    My ES-125 with its sound post and missing tone bars sounds better than all other ES-125s I have compared it too (lots of jamsessions with different other 125s): dry, woody, thunky, very good definition, clarity without being sharp. But I am probably biased..... ;-)
    Last edited by Little Jay; 10-24-2020 at 04:01 AM.

  9. #33

    User Info Menu

    Since a few years I have this feeling, if I can restart my life I would be luthier...which is way far my daily job, so please bear with me. Can anybody explain would be the impact of those manufacturing errors? Is it soundwise, or mechanical stability... I have no clue...

  10. #34

    User Info Menu

    Quote Originally Posted by Gabor
    Since a few years I have this feeling, if I can restart my life I would be luthier...which is way far my daily job, so please bear with me. Can anybody explain would be the impact of those manufacturing errors? Is it soundwise, or mechanical stability... I have no clue...
    Here are my amateur comments.

    1. The sloppy work on that ES-275 is an embarrassment to Gibson. The guitar design was not executed, and it should have never left Memphis.

    2. The majority of the customers wouldn't have done a mirror exam and caught it.

    3. Most players and listeners couldn't tell the difference, especially amplified, even if there was a difference.

    4. The longevity of that instrument likely was not affected by its bracing.

    So is it no harm, no foul? No, not in my opinion. It's like when Gibson started making the "swiss cheese" LPs without telling the public. We are entitled to know what's under the hood, that's all.

  11. #35

    User Info Menu

    Quote Originally Posted by Lobomov
    Meh ... I'm sure Eastman has it share of lemons too
    I am sure this is not the case. Eastman has its handicap, I mean MIC, and that brand must prove continously to increase or even keep its market share. As opposite, Gibson is sitting on his throne. Not the same situation.